Cape Town, South Africa—Take shorter and fewer showers. Skip a shave. Sweep, don’t hose. Collect rainwater. Serious drought, every drop counts. For months, posters bearing these slogans have hung from lampposts in and around this city at the southern tip of Africa, beset by years of drought. But those exhortations don’t seem to have done enough; during those same months, headlines have blared to Capetonians and to others around the world that Cape Town was about to reach “Day Zero,” the day the metropolis would run out of usable tap water. At one point, Day Zero was expected to arrive this very month. The world watched in fascination and dread.

Today, however, the downward trend that seemed inexorable just weeks ago doesn’t seem so certain anymore. Early this year, Capetonians began to sharply lower their water use. Such changed behavior, along with decreased consumption in the agricultural sector, prompted authorities to push Day Zero back to this June. Then, in March, officials reset their estimation to some unspecified date in 2019. In the meantime, a few rainstorms have blown through the parched city. Although those downpours have done virtually nothing to relieve the water shortage, they and the retreat of Day Zero have brought something that’s been less abundant than water in the troubled city: hope.

Facing the Unknown

Although the narrative about Cape Town has turned distinctly upbeat in just a few weeks, the city’s prospects are by no means clear. The so-called Mother City, which holds roughly 4 million people, still finds itself in the middle of a perfect, dry storm, one in which years of drought coupled with rapid population growth have set the stage for a catastrophe. Although two oceans—the Atlantic and the Indian—surround two sides of the city, water levels in the city’s reservoirs are still sinking. In place of regular pronouncements of impending doom, the city now endures a tense waiting game as South Africa moves into its winter, which is when Cape Town tends to get most of its annual rainfall.

“So far, we’ve had below-average rainfall. It might still turn around, and we will know by the end of May.”“We don’t really know” what the future holds for Cape Town, Piotr Wolski, a hydroclimatologist at the University of Cape Town, told Eos. “So far, we’ve had below-average rainfall. It might still turn around, and we will know by the end of May.”

Reservoir Levels on the Wane

Cape Town depends on six main dams and eight minor dams, which together hold about 90,000 megaliters of water. The dams are above the city in mountains that form part of the Cape Fold Belt, which arose during the Paleozoic and was once connected to mountain ranges now found on other continents. Table Mountain, which cradles Cape Town and is often draped in a cloud layer that locals call “the tablecloth,” is part of this mountain chain.

“Cape Town’s main catchment area is the Mountain Fynbos catchment, located to the east and northeast of the city,” said Jessica Fell, a hydrologist at the University of Cape Town’s Future Water Institute. “The dams are filled by winter rainfall that runs off the catchment area into streams and rivers, which then feed the dams.” But the winter rains began to wane in 2014 and 2015, and water storage behind the dams dropped from 87.4% to 73.9% of full capacity. Like the trend at Nevada and Arizona’s Lake Mead, the drop continued, and by February of this year the reservoirs were at 25.5% capacity, with no signs of abatement. Shortly before this story was published, the city’s reservoirs hovered at 20.0% capacity.

A recent drive to the dam revealed not a reservoir but a playa.Theewaterskloof Dam is in the fold mountains, and it holds more water than the other 13 dams combined. A recent drive to the dam revealed not a reservoir but a playa, one where dust storms swirled over a trickling of water that snaked around what had once been an island, atop which stood a white cross.

Fell described Cape Town as a “canary in a coal mine” because what is happening to the city is what other cities around the world can expect to face as temperatures continue to climb in the coming century. She added that lessons learned in Cape Town about dealing with times of no water will be applicable elsewhere.

Growing Population, Rising Temperatures

As water levels have fallen, Cape Town’s population has been on the rise. The city’s population almost doubled over the past 20 years, going from 2 million to 4 million, which brought an increase in demand for water. As people flooded in, the city prepared for water shortages. “The city of Cape Town, along with the national and provincial government, have been planning long-term water demand management programs for many years to augment the Western Cape Water Supply System,” said Fell. This system includes the dams as well as pump stations, pipelines, and tunnels. “Water shortages were predicted in the city by 2020, and plans had been put in place for augmentation schemes to deal with this; however, the severe, unprecedented drought derailed these plans,” she said.

It is unclear just how much that climate change is contributing to the drought. “We can clearly say that temperatures have been rising due to climate change, and that does increase water demand,” said Bob Scholes, a systems ecologist at the University of the Witwatersrand in Johannesburg. “The biggest factor has been the steadily rising water use, driven by urbanization.”

Cape Town residents queue for water at Newlands spring. Credit: Lucas Joel

“Luck just ran out for Cape Town,” Scholes continued. “In this case, it did so after three subaverage rainfall years.” He added that what is happening in Cape Town is not unique and that a similar drought almost befell Johannesburg 2 years ago.

Still, the odds of a drought of this magnitude occurring are slim, explained Wolski. “The return period for the drought comes to be longer than 1 in 300 years,” he said. This, he explained, implies that the drought is likely due less to anthropogenic climate change and more to natural variability. “Long-term rainfall trends are weak and spatially variable in the region, with some locations getting wetter and some drier in the last 100 years,” he said. “The link between these trends and anthropogenic climate change is not clear at the moment.”

Adapting, with an Eye on the Sky

The drought’s costs are high: About 30,000 seasonal farmworker jobs were lost, and about 25% of orchards and vineyards died out.“Act Now. We Must #DefeatDayZero” reads another sign hanging in Cape Town. Like a runaway train coming to a slow crawl, the city’s water consumption has slowed to a trickle. Many Capetonians have curbed their water use by recycling their gray water. A large number of households, for instance, collect shower water in a basin and then use that water for other things, like flushing toilets. Such changes, along with decreased farm use, helped ensure Day Zero’s delay, but the costs are still high: About 30,000 seasonal farmworker jobs were lost, and about 25% of orchards and vineyards died out, said University of Cape Town climate researcher Mark New during a recent lecture at the University of Leeds in the United Kingdom.

In a recent, troubling development, Marchwater use began to climb, despite the fact that the city’s reservoirs now have less water in them than when the water crisis hit fever pitch earlier in the year. Fell speculates that Day Zero’s delay is causing denizens to “slack,” but she affirms that thinking that the city is in the clear is inaccurate.

Water restrictions in Cape Town remain tight, with each person supposed to use only 50 liters of water each day. (The average U.S. household uses about 1,136 liters each day, and one toilet flush can use as much as 11 liters.) The 50-liter mandate applies to Capetonians as well as to people visiting the city for tourism or for work, although critical areas like hospitals and the city’s business district do not have such restrictions in place. Had Day Zero hit this year, city leaders had plans to open 200 water distribution points, which would have been the only places people could get their water. Those plans are now scrapped, but what 2019 will look like is anyone’s guess.

Although holding out hope for rain, citizens are queuing for water.Although holding out hope for rain, citizens are queuing for water. One place where they queue is at Newlands spring, near the University of Cape Town. There, people carrying plastic water jugs of many sizes stand in line in front of water dribbling from PVC pipes. One man, a local farmer, said he had been coming to the Newlands spring for many years and had never seen it so busy. He lowered his voice when he said what he thinks is driving the sudden deluge of people: “fear.”

Eos is a source for news and perspectives about Earth and space science, including coverage of new research, analyses of science policy, and scientist-authored descriptions of their ongoing research and commentary on issues affecting the science community.